SAN FRANCISCO — On the eighth day of her son’s life, Julia Query welcomed friends and family to celebrate his birth and honor their Jewish heritage.

But there was no crying, no scalpel, no blood, no “mohel” — the person who traditionally performs ritual circumcisions in the Jewish faith. In fact, Elijah Rose’s “bris” differed markedly from the ceremony long used to initiate Jewish boys into a covenant with God: There was no circumcision.

“I knew before I was even pregnant that I would not circumcise,” said Query, 39, a San Francisco filmmaker whose son was born in 2002. “It’s not like you’re just cutting a piece of paper off a pad — there’s no ‘cut here’ line. It’s not made to be cut off, and I would never, ever do that to my baby.”

Query is among a growing number of American parents refusing circumcision, in which the foreskin is removed from the penis.

According to data from the National Health and Social Life Survey, the U.S. circumcision rate peaked at nearly 90 percent in the early 1960s but began dropping in the ’70s. By 2004, the most recent year for which government figures are available, about 57 percent of all male newborns delivered in hospitals were circumcised. In some states, the rate is well-below 50 percent.

Experts say immigration patterns play the biggest role in the decline, which is steepest in Western states with big populations from Asian and Latin American countries where circumcision is uncommon. The trend has also accompanied a change in Americans’ attitudes toward medicine and their bodies.

“The rates of drug-free labor and breast-feeding all rose during the 1980s, while the initial declines in male circumcision rates began during the 1980s as well,” said Katharine Barrett, an anthropology lecturer at Stanford University. “It may have been part and parcel of the wider effort to reclaim bodies — adult female and infant male — from unnecessary and potentially harmful medical interventions.”

Circumcision remains the nation’s most common surgery, and the United States is one of the few developed countries where a majority of baby boys are circumcised. But circumcision is a heated issue and the subject of vehemently pro and anti Web sites.

“We were all circumcised when I was born,” said R. Louis Schultz, 79, a New Yorker and author of “Out in the Open: The Complete Male Pelvis.”

“People thought it could ward off masturbation or disease, and those funny attitudes have really changed. Now people are saying, ‘Why do it?’ “

Many doctors still recommend circumcision because of some evidence that it reduces the risk of penile cancer, urinary-tract infections, HIV and perhaps other sexual-transmitted diseases.

But circumcision opponents say the medical benefits are dubious. Penile cancer, for example, is extremely rare. Since 1999, the American Academy of Pediatrics has not endorsed routine circumcision.

The debate escalated in February, when studies found that heterosexual men in Africa who were circumcised had HIV infection rates up to 60 percent lower than uncircumcised men. Because of those studies, the American Academy of Pediatrics is taking another look at its policy.

About one in three males worldwide is circumcised. In the United States, the rates vary widely by region.

It is most prevalent in the upper Midwest. In 2004, according to data compiled by the federal Agency for Healthcare Research and Quality, more than 79 percent of newborn boys in the Midwest were circumcised before leaving the hospital.

In the fast-growing West, the rate declined dramatically — from 64 percent in 1979 to just under 32 percent in 2004.

In California, the rate of hospital circumcisions among newborns was 21 percent. California — which has more immigrants than any other state — had the lowest circumcision rate in the study, which had comprehensive data on 27 states.